At present, there are no Citrus cultivars resistant to bacterial canker (Xanthomonas axonopodis pv. citri) (Xac), and/or citrus Huanglongbing (ex greening) caused by Candidatus Liberibacter asiaticus (Las). Indeed, no genetic resistance to these microbial pathogens has ever been found within the Citrus genus. Conventional cross-breeding efforts to produce resistant cultivars have been hindered by the complex reproductive biology and long life cycle of Citrus spp.